Fix passing --classpath-dir to dex2oat for split apks.

Merged wrong version of CL in by mistake. CL should have been
cherry-picked from cc5c4e32.

Bug: 34169257
Test: cts-tradefed run singleCommand cts -d --module
CtsAppSecurityHostTestCases -t android.appsecurity.cts.SplitTests

Change-Id: Ibebcdce1c9ab0de3254727c8dfc3d0de18932f1c